The ALCO RS-27 (specification DL-640) was a diesel-electric locomotive built by ALCO between December 1959 and October 1962.
Only 27 examples were manufactured.[1] With ALCO's introduction of the Century Series line in 1963, the C-424 (specification DL-640A) replaced the RS-27 in the builder's catalog. Today, the Minnesota Commercial Railway has the only two RS-27s left in existence; however both have been placed into storage.[2]